Page 13 - Jan-Feb 2018
P. 13

                                                                                     FocusVVSDSDuu¨¨yykkWtWthh QQ¨¨ddll

   These materials survive forty           Indigenised AA2519-T87 plate (t = 10 mm)  10 mm and 15 mm and heat treated
(40) days of SCC tests (when loaded                 produced at BALCO, Korba         to T87 temper. The 15 mm thick
against 90 % of the 0.2 % proof stress                                               plates of the alloy were subjected to
value in LT direction) as per ASTM         this aluminium alloy has been utilised    ballistic tests against 7.62 mm x 54
G 47-98. Under DMRL’s technical            to reduce the weight of the vehicle. No   mm AP (I) ammunition at DMRL.
guidance, twenty one (21) tons of these    information is available regarding the    The test requirement is 7.62 mm x 54
materials were produced at BALCO           processing details of this material in    mm AP(I) at average proof velocity of
within a record six (6) months time        the literature.                           509 m/s. The tests showed six (6) per
during 2014-2015. Inspection and                                                     cent superior results with reference to
certification of these materials were         The alloy AA2519 contains high         MIL-STD-46192C (MR).
carried out by Controllerate of Quality    copper (slightly less than what the
Assurance (Establishment) [CQA(E)],        alloy AA2219 contains) and also small        These materials were tested for
Pune.                                      amounts of magnesium. Because             weldability, stress corrosion cracking
                                           of the presence of magnesium, the         resistance, sub-zero temperature
   L&T fabricated one set, i.e., five      procedure of melting and casting of the   tensile strength, fracture toughness,
(5) numbers of Sarvatra bridges            alloy considerably differs from those     etc. for product qualification purposes.
and delivered to BEML in 2015. The         of the alloy AA2219. The presence of      All essential properties were achieved
bridges qualified the structural tests at  magnesium makes the alloy prone to        for these materials.
L&T, Talegaon prior to their dispatch      hot cracking during solidification.
to Bharat Earth Movers Limited                                                       Indigenously Built
(BEML). Following this, the bridges           DMRL provided optimum alloy            Combat Aircraft
underwent successful trials at various     composition, melting and casting
locations of the country. Extrusions       procedure as well as thermal and             Aluminium–zinc–magnesium–
of the alloy RDE40M, produced by           mechanical processing parameters for      copper base 7xxx series represents the
Hindalco using a modified aging heat       the production of this alloy at BALCO,    class of highest strength aluminium
treatment, prescribed by DMRL, are         Korba.                                    alloys that is produced using the
now ready for the manufacture of                                                     ingot metallurgical route. These alloys
components for Sarvatra bridging              The alloy was processed in the         are non-weldable and utilised for
system.                                    form of plates having thicknesses of      structural components where strength
                                                                                     is the primary requirement.
Futuristic Infantry
Combat Vehicle (FICV)                                                                   An additional advantage of
                                                                                     copper-bearing aluminium-zinc-
   Aluminium alloy AA2519 is used                                                    magnesium alloys is that they could be
in the state-of-the-art Advanced                                                     heat treated to suitable T7x51/ T7x52
Amphibious Assault Vehicle (AAAV).                                                   tempers to significantly improve
The AAAV is an amphibious                                                            the exfoliation and stress corrosion
armoured personnel carrier wherein                                                   cracking resistance. An important

Indigenised AA2519 (a) Slab, and (b) T87 Plates  Top and bottom sides of the 15 mm thick AA2519-T87 plate subjected to the
         (t = 15 mm) produced at BALCO                          ballistic test against 7.62 x 54 mm AP (I) ammunition

Aluminium Alloy Technologies for Advanced Defence Systems  	 January-February 2018 13
   8   9   10   11   12   13   14   15   16   17   18